Alkyl-stilbene liquid-crystal compounds

ABSTRACT

There is disclosed the preparation of novel p-methoxy-alkyleneoxy-p&#39;&#39;-n-alkyl-stilbene liquid-crystal compounds of the structure:   WHERE X AND Y ARE THE SAME OR DIFFERENT INTEGERS OF 1 TO 10, TYPICALLY 1 TO 5.

United States Patent [1 1 Steiger et al.

[ ALKYL-STILBENE LIQUID-CRYSTAL COMPOUNDS [75] Inventors: Edward LSteiger; Heinz J. Dietrich,

both of Toledo, Ohio [73] Assignee: Owens-Illinois, Inc., Toledo, Ohio[22] Filed: Jan. 8, 1971 [21] Appl. No.: 154,688

[56] References Cited UNITED STATES PATENTS 2,346,049 4/1944 Rohrmann260/613 A 1 June 26, 1973 10/1968 Barany et al 260/613 R X 11/1946Schwarzkopf 260/613 A Primary Examiner-Bernard Helfin Attorney-Donald K.Wedding et al.

[57] ABSTRACT There is disclosed the preparation of novelp-methoxyalkylene-oxy-p'-n-alkyl-stilbene liquid-crystal compounds ofthe structure:

where x and y are the same or different integers of 1 to 10, typically 1to 5.

2 Claims, No Drawings 1 STABILIZATION OF THERMALLY UNSTABLE DMT BYMIXTURE OF C -C ALKANOL MATERIAL AND CERTAIN COBALT SALT MATERIALTI'IEDISCLOSUR'E where x and y are the sameor different integers of l"to 10, typically l to 5.

The novel liquid-crystal compounds of this invention are prepared byreacting para-methoxy-alkyleneoxybenzaldehyde andpara-alkyl-benzyl-magnesium halide to form an intermediate product, andthen heating the intermediate product so as to dehydrate it to the finalp-methoxy-alkylene-oxy-p'-n-alkyl-stilbene product. The reaction is asfollows:

The diazotization reaction (3) has been illustrated with reference tosodium nitrite. However, any source of nitrite anion (NOE) may be used.Examples include not by way of limitation alkali nitrite'such as sodiumnitrite, potassium nitrite, and lithium nitrite; alkaline earthnitritesu'ch, as barium nitrite, calcium nitrite, and

magnesium nitrite; other inorganic nitrites such as ammonium nitrite;and organic nitrites such as alkyl nitrites of l to 10 carbons.

The HZ acid medium of reaction (3) is selected from hydrogen halideswhere Z is typically chloride, iodide, or bromide. The acids ofreactions (5) and (7) may be the same.

Y is an integer as described hereinbefore.

There are many alternatives to the LiAlH, of reaction (6), e.g., such asdiisobutylaluminum hydrideor sodium bis (Z-methoxyethoxy) aluminumhydride.

Reaction (8) is conducted with elemental Mg in the presence of diethylether.

The para-methoxy-alkyleneoxybenzaldehydes of this invention are preparedby a first reaction of parahydroxybenzaldehyde and potassium hydroxidein a dimethyl formamide-benzene (1:1) solvent mixture, refluxing atabout 100C to remove the water of reaction azeotropically, and reactingthe product of the first reaction with an appropriate methoxyalkylhalide. The solution is then heated to reflux for about 4 to 6 hours.After the solvents are removed in vacuum, the products are separatedfrom the inorganic residues by a water immiscible solvent followed byfractionation to recover the requiredparamethoxy-alkyleneoxybenzaldehyde.

The following equations are representative:

omowmnocnon-om Q men-12y.

In the process x and y are as defined hereinbefore. (9) The halogen atomZ is typically selected from BR, I, or 1ro 0 050 K011 'Ko@cuo Cl. l t

The dehydration reaction (2) may be in the absence 45 (10) or presene ofdehydrating agents. Typical dehydrating agents include potassium acidsulfate, thionyl chloride, and hydrogen sulfate.

The resulting substitutedstilbene liquid-crystal compound may be amixture of cis and trans isomers. If desirable, these may beappropriately separated by chromatography or other suitable means.

The para-alkyl benzyl magnesium halide may be prepared as follows:

The appropriate methoxyalkyl halide is prepared by the chlorination of amethoxy alcohol, CH3O(CH2 )IOI-I where x is as defined above.

The liquid-crystal compounds prepared in accor- Mg: 110,111... C) only.0,111... 0112mm dance with this invention may be utilized in displaydevices, especially of the electronic type.

Such devices typically comprise a thin layer of liquid crystalssandwiched between two sheets of glass. Normally, the thin layer ofliquid-crystal material is clear, but when an electric field is appliedto it, some portions or regions of the material become turbulent so asto scatter light. By controlling the size and shape of the turbulentregions, images can be formed. Primarily, this effect is obtained by useof liquid-crystal materials of the nematic type.

In one particular embodiment, a liquid-crystal material is sandwiched asa dielectric in a parallel plate capacitor with one electrodetransparent and the other electrode either transparent or reflecting.The liquid is kept between the electrodes by capillary action, sinceelectrode spacings are of the order of one-half mil. An applied do. orlow-frequency (less than 100 Hz.) field of more than 30,000 volts percentimeter changes the cell from transparent to turbulent in a fewmilliseconds. Depending upon the liquid-crystal composition, the opaqueeffect may remain even after the field is removed. In other words, anoptical signal may be maintained with no applied power. The cell can beturned clear again by applying a higher-frequency (greater than 700 Hz.)signal. The sample remains clear after the signal is removed.

Additional embodiments of liquid-crystal electrooptical devices aredisclosed and illustrated in U. S. Letters Pat. Nos. 3,401,262 and3,410,999; Proceedings of the IEEE, Vol. 56, No. 12, Dec., 1968, pages2146 to 2149; The Glass Industry, August, 1968, pages 423 to 425;Chemical and Engineering News, Sept. 30, 1968, pages 32 and 33; PhysicsToday, July, 1970, pages 30 to 36; Electronics, July 6, 1970, pages 64to 70; U. S. Letters Pat. No. 3,322,485 to Williams.

It is also contemplated using the liquid-crystal compounds in a chargestorage display/memory device, especially multiple gas dischargedisplay/memory panels which have an electrical memory and which arecapable of producing a visual display or representation of data such asnumerals, letters, television display, radar displays, binary words,etc.

Multiple gas discharge display and/or memory panels of the type withwhich the present invention is especially concerned are characterized byan ionizable gaseous medium, usually a mixture of at least two gases atan appropriate gas pressure, in a thin gas chamber or space between apair of opposed dielectric charge storage members which are backed byconductor (electrode) members, the conductor members backing eachdielectric member being transversely oriented to define a plurality ofdiscrete discharge volumes and constituting a discharge unit. In someprior art panels the discharge units are additionally defined bysurrounding or confining physical structure such as by cells orapertures in perforated glass plates and the like so as to be physicallyisolated relative to other units. In either case, with or without theconfining physical structure, charges (electrons, ions) produced uponionization of the gas of a selected discharge unit, when properalternating operating potentials are applied to selected conductorsthereof, are collected upon the surfaces of the dielectric atspecifically defined locations and constitutes an electrical fieldopposing the electrical field which created them so as to terminate thedischarge for the remainder of the half cycle and aid in the initiationof a discharge on a succeeding opposite half cycle of applied voltage,such charges as are stored constituting an electrical memory.

Thus, the dielectric layers prevent the passage of any conductivecurrent from the conductor members to the gaseous medium and also serveas collecting surface for ionized gaseous medium charges (electrons,ions) during the alternate half cycles of the A.C. operating potentials,such charges collecting first on one elemental or discrete dielectricsurface area and then on an opposing elemental or discrete dielectricsurface area on alternate half cycles to constitute an electricalmemory.

An example of a panel structure containing nonphysically isolated oropen discharge units is disclosed in U. S. Letters Pat. No. 3,499,167issued to Theodore C. Baker et al.

An Example of a panel containing physically isolated units is disclosedin the article by D. L. Bitzer and H. G. Slottow entitled The PlasmaDisplay Panel A Digitally Addressable Display with Inherent Memory,Proceeding of the Fall Joint Computer Conference, IEEE, San Francisco,California, Nov. 1966, pages 541-547. Also reference is made to U. S.Letters Pat. No. 3,559,190.

In the operation of the panel, a continuous volume of ionizable gas isconfined between a pair of dielectric surfaces backed by conductorarrays forming matrix elements. Typically one or more dielectric layersare photomissive. The cross conductor arrays may be orthogonally related(but any other configuration of conductor arrays may be used) to definea plurality of opposed pairs of charge storage areas on the surfaces ofthe dielectric bounding or confining the gas. Thus, for a conductormatrix having H rows and C columns the number of elemental dischargevolumes will be the product H X C and the number of elemental ordiscrete areas will be twice the number of elemental discharge volumes.

In addition to the matrix configuration, the conductor arrays may beshaped otherwise. Accordingly, while the preferred conductor arrangementis of the crossed grid type as shown herein, it is likewise apparentthat where an infinite variety of two dimensional display patterns arenot necessary, as where specific standardized visual shapes (e.g.,numerals, letters, words, etc.) are to be formed and image resolution isnot critical, the conductors may be shaped accordingly.

The gas is one which produces light (if visual display is an objective)and a copious supply of charges (ions and electrons) during discharge.In an open cell Baker et al. type panel, the gas pressure and theelectric field are sufficient to laterally confine charges generated ondischarge within elemental or discrete volumes of gas between opposedpairs of elemental or discrete dielectric areas within the perimeter ofsuch areas, especially in a panel containing non-isolated units.

As described in the Baker et a1. patent, the space between thedielectric surfaces occupied by the gas is such as to permit photonsgenerated on discharge in a selected discrete or elemental volume of gasto pass freely through the gas space and strike surface areas ofdielectric remote from the selected discrete volumes, such remote,photon struck dielectric surface areas thereby emitting electrons so asto condition other and more remote elemental volumes for discharges at auniform applied potential.

With respect to the memory function of a given discharge panel, theallowable distance or spacing be- We claim: tween the dielectricsurfaces depends, inter alia, on the 1. As a composition of matter, acompound having frequency of the alternating current supply, the disthechemical structure:

tance typically being greater for lower frequencies. y W Y .i

In the practice of this invention, it is contemplated 5 that aparticular liquid crystal may be prepared and/or LHO(CHZ)O@CHZCHutilized alone or in combination with other liquidcrystal compositionsof the same or different family, e.g., such as a mixture of 2 or morecompositions. This may be especially desirable since mixtures of 10 2.The invention of claim 1 wherein x and y are the pounds may have lowertransition temperatures than same or different integers of I to 5'themdividual compounds.

where x and y are the same or different integers of l to 10, saidcompound exhibiting liquid-crystal properties.

2. The invention of claim 1 wherein x and y are the same or differentintegers of 1 to 5.